An ability to detect and classify small particles in a fluid stream (air or liquid) is of great use in many fields. For example, detecting harmful particles in air (e.g., outdoors or inside a building) or in water (e.g., a city water supply) may be used to protect people from non-lethal particles, such as mold spores, or lethal particles, such biological agent particles. In addition, a large class of particle detector systems referred to as flow cytometers are based on the detection and classification of particles in a fluid stream. Typically, such systems detect a particle by illuminating it with radiation (ultraviolet to infrared) and detecting the resulting particle emitted radiation (elastic scattering and/or fluorescence).